Mia: s + 5
Raul: 3(s + 5)
Sofia: s
Make an equation where all of their stamps add up to 100.
s + 5 + 3(s + 5) + s = 100
Distribute 3 inside the parentheses.
s + 5 + 3s + 15 + s = 100
Combine like terms.
5s + 20 = 100
Subtract 20 from both sides.
5s = 80
Divide both sides by 5.
s = 16
Plug in s into their equations.
Mia: s + 5 ⇒ 16 + 5 = 21
Raul: 3(s + 5) ⇒ 3(16 + 5) = 63
Sofia: s ⇒ 16
